A novel endogenous antimicrobial peptide CAMP211-225 derived from casein in human milk.

A large number of bioactive peptides derived from breast milk have been identified to be multifunctional having anti-inflammatory, immunoregulation and antimicrobial activity. Here, we report that an endogenous peptide from β-casein 211-225 amino acid from human breast milk (hereafter called CAMP211-225) presents specific antimicrobial activity against pathogenic E. coli and Y. enterocolitica. CAMP211-225 is a novel peptide that occurs at higher levels in preterm milk than in term milk. The minimal inhibitory concentrations (MIC) of CAMP211-225 against E. coli and Y. enterocolitica are 3.125 μg/ml and 6.25 μg/ml, respectively, and the antimicrobial activity of CAMP211-225 was also confirmed by disk diffusion assay. Further studies by fluorescence staining, scanning electron microscopy and a DNA-binding assay revealed that CAMP211-225 kills bacteria through a membrane-disrupting mechanism, but not by binding to intracellular nucleic acids. Neonatal necrotizing enterocolitis (NEC) is a devastating gastrointestinal disease in neonatal intensive care units. In our study, CAMP211-225 administration effectively reduced ileal mucosa damage in an experimental NEC mice model. These results suggest that the antimicrobial peptide CAMP211-225 may have potential value to prevent and treat neonatal infections.